The invention relates to modular solid-fuel rocket propelling charges with different propellant components and other components, for instance fuel, oxidants, energy-enhancing admixtures, binders, additives, coatings, inhibitors, etc., which can be completely or partially fragmented, i.e. not in the form of the conventional homogeneous mixture, but in the form of one or more macroscopic combustible elements having any suitable configuration, whereby all or single components can also consist of substances which have first to be brought to a sufficiently solid state through cooling.
Thereby the invention relates to the technical field of rocket propellants and their production, construction and safe storage of solid-fuel propellant charges. In this connection the term solid-fuel propelling charges defines the simple or composite propellant block existing in a certain geometric shape, including possible inserts or attachments which are mounted for various purposes and are mostly consumed through combustion.
It is state of the art in this type of solid-fuel rocket propelling charges according to the patent application DE 197 56 794 A1 of the applicant dated Dec. 19, 1997 that the propellant charge be at least partially fragmented, i.e. at least one of the components is not present in the conventional intimate mixture with the other components, but is present in the form of one or more macroscopic combustible elements with any suitable geometric configuration. The combustible elements are chemically insulated from each other by means of appropriate coatings, and if necessary, can be at the same time mechanically interconnected. Furthermore through a special selection of their composition, the combustible elements can be suited to serve as modules with different functions, such as ignition, combustion promoters, gas production, etc. The combustible elements can have particularly the shape of disks, whose outer surface accommodates the contour of the rocket combustion chamber, while inside-they can have one or several bores with a suitably shaped cross section surface, which due to their arrangement in sequence form one or more combustion channels with constant or variable cross section surface, or they can be lodged with various, freely selectable cross section shapes in a coherent matrix of the respective other fuel component, for instance oxidant-rich elements completely or partially embedded in a fuel matrix.
It is state of the art in conventional, i.e. storage-capable solid-fuel propellants to arrange the propellant components in layers, in so-called xe2x80x9csandwich propellantsxe2x80x9d, however this has not resulted in particular advantages and therefore has not been widely used.
Cryogenic solid bodies as propellants have been tested at the USAF Phillips Lab (Edwards) since 1994 in a xe2x80x9cHigh-energy Densityxe2x80x9d program. In 1997 papers relating to hybrids (i.e. propellants with liquid and solid fuel components with frozen hydrocarbons as solid component have been published (see C. Larson, USAF-Phillips Lab, 3rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Washington State Convention and Trade Center, Seattle, Wash. Jul. 6-9, 1997, AIAA-96-3076).
This known state of the art is fraught with the problem that modular, cryogenic solid-fuel propellant charges require constant cooling in order to maintain their aggregate state in a normally tempered surrounding. In the absence of cooling, these propellant charges can melt, evaporate, so that in many ways this can trigger the development of very dangerous situations.
It is the object of the invention to make available modular solid-fuel rocket propelling charges of the kind mentioned in the introduction, so that the development of dangerous situations due to cooling failure while the output of the carrier rocket increases, is drastically reduced.
This object is achieved in modular solid-fuel rocket propelling charges of the aforementioned kind having the characteristic features of claim 1.
Advantageous embodiments are defined in the dependent claims.
Depending on the combination of the features defined in claim 1 with the advantageous embodiments of the invention defined in the dependent claims, the situation can be considerably improved with regard to all or some of the indicated problems. The modular solid-fuel rocket propelling charge makes possible the selection of fuel and oxidants from a wide variety and can be separately formed into combustible elements, which combined can result in the desired propellant geometry. The therefor required aggregate state is, if needed, produced and maintained through a corresponding cooling. The term xe2x80x9cfragmented propelling chargexe2x80x9d (here synonymous with xe2x80x9cmodularxe2x80x9d, xe2x80x9cseparatedxe2x80x9d, or xe2x80x9cdividedxe2x80x9d propellant charge) refers primarily to the separation of the main components (fuel and oxidant). An appropriate synonym for xe2x80x9cmodular solid-fuel rocker propelling chargexe2x80x9d is xe2x80x9cmultiple internal hybrid propulsionxe2x80x9d.
According to the invention the following advantageous effects can be achieved:
The propellant charges of the invention simplify considerably the production of solid fuel propellant charges. Many dangerous procedures are avoided, production in series is made affordable. Considerable cost reductions can be expected. These statement are valid, independent of possible complications which can be caused by cryogenic solid substances.
The propellant charges of the invention avoid the large phase border surfaces of conventional propellant charges. As a result in the case of propellants suitable for warm storage an increase of the long-term storage capability is to be expected, besides the combustible elements can be separated from each other by insulating foil.
Cryogenic fuels can not be stored, but are less reactive than the warm ones due to the low temperatures. In certain cases this can make possible the use of special high-energy substances, which would be to reactive as liquids or gases. The propellant charges of the invention allow any fuel combination to be realized as a monergol solid-fuel propellant. This reaches from storageable or cryogenic liquid monergol and diergol propulsion systems over hybrid and quasi-hybrid propulsion systems, suspension (slurry) propulsion systems and tribrids up to all triergols. Therefore drastic increases of the Isp (theoretical specific impulse) can be expected, not only compared to the conventional solid-fuel propellants, but even compared to the state of the art liquid propulsion systems (see here R.E.LO:DFVLR-Stuttgart: xe2x80x9cChemische Wasserstoffaufheizung durch tribride Verbrennungxe2x80x9d, Chemie-Ingenieur-Technik (1967)39, volume 15, pages 923-927/R.E.LO: Technical Feasibility of Chemical Propulsion Systems with very high Performance, Proceedings of the XVIIIth Astronautical Congress, Belgrade, Sep. 25-29, 1967, pp. 121-132/R.E.LO, DFVLR-Lampoldshausen: Theoretische Leistungen des Raketentriebstoffsystems F2,O2/LiH, Al/H2 und einfacher Teilsystemexe2x80x9d, DLR Mitt. 69-21 (December 1969)/R.E. LO, DFVLR Lampoldshausen: xe2x80x9cChemische Wasserstoffaufheizung durch Verbrennung von Aluminium mit Sauerstoff oder FLOXxe2x80x9d, DLR-Mitt. 70-03 (February 1970)/R.E.LO, DFVLR Lampoldshausen: xe2x80x9cQuasihybride Raketenantriebexe2x80x9d, Raumfahrtforschung, Vol. 4, April 1970).
The propellant charges of the invention make possible to create solid propellant charges which are as environmentally friendly as possible, through an appropriate selection of fuels, for instance solid hydrogen/solid oxygen.